Musnad Ahmad 652:3

Hassan and Yunus narrated to us, they said: Hammad bin Salamah narrated to us, from Asim bin Bahdalah, from Khaythamah bin Abd al-Rahman, from al-Nu’man bin Bashir, that the Messenger of Allah, peace and blessings of Allah be upon him, said: "The best of this nation is the generation in which I was sent, then those who follow them, then those who follow them, then those who follow those who follow them." Hassan said: "Then peoples will arise whose oaths will precede their testimonies, and their testimonies will precede their oaths."